Heat-Treatment Furnace Atmosphere Dilution to Limit Oxidation
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Solution Overview
Problem
The transition from fossil fuels to hydrogen in heat treatment furnaces for metals, particularly steels, leads to increased water vapor pressure, promoting oxidation, scale formation, and altered grain structures, adversely affecting product properties.
Innovation Solution
Use a fuel gas with at least 10% hydrogen and dilute the combustion gas with a water vapor-free and/or hydrogen-free gas to maintain a lower partial water vapor pressure, using renewable energy-generated hydrogen and oxygen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hydrogen-containing fuel is used to replace natural gas in the heat treatment furnace, then decarbonization and environmental friendliness are improved, but the partial water vapor pressure in the furnace atmosphere increases, leading to increased oxidation and scale formation on metal surfaces
Solution Approach 1:
An intermediary gas (nitrogen or carbon dioxide) is introduced as a mediator between the hydrogen combustion process and the metal surface. This intermediary gas dilutes the water vapor in the furnace atmosphere, preventing direct interaction between high concentrations of water vapor and the metal surface, thereby reducing oxidation and scale formation while maintaining the benefits of hydrogen fuel usage
Solution Approach 2:
The composition parameters of the furnace atmosphere are actively controlled by adjusting the ratio of intermediary gas to combustion gas. By changing the concentration of water vapor through gas mixing, the adverse effects on metal surface are mitigated while preserving the decarbonization advantage of hydrogen fuel
2Object-generated harmful factors
If the furnace atmosphere is flooded with water vapor-free gas to reduce partial water vapor pressure, then oxidation and scale formation are reduced, but the complexity of the gas control system increases
Solution Approach 1:
An inert or less reactive gas (nitrogen or carbon dioxide) is used to create a modified furnace atmosphere that is less conducive to oxidation. This inert gas environment protects the metal surface from reacting with water vapor, reducing scale formation without requiring complex active control mechanisms
Solution Approach 2:
The intermediary gas serves as a simple mixing component that passively controls water vapor concentration through diffusion and convection, avoiding the need for complex active control systems while achieving the desired reduction in oxidation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Maintains furnace atmosphere compatibility with natural gas operation, reducing oxidation and scale formation, preserving product quality and mechanical properties.
Implementation Method 1
at least one burner (2) which is operated with a fuel gas (3) and an oxygenous gas (4) that are combusted to give a combustion gas (10)
Implementation Method 2
the heat treatment furnace (1) is additionally flooded with a water vapor-free and/or hydrogen-free gas (5), as a result of which the water vapor-free and/or hydrogen-free gas (5) mixes with the combustion gas (10) so as to bring about a partial water vapor pressure of the mixture in the furnace atmosphere (9)
Implementation Method 3
Essential features of the invention are that hydrogen is used in the fuel gas (3) with a proportion of at least 10% by volume and that the heat treatment furnace (1) is additionally flooded with a water vapor-free and/or hydrogen-free gas (5)
Data Source
AI summary
A method of establishing a furnace atmosphere in a directly heated heat treatment furnace is provided. A heat treatment furnace has at least one burner which is operated with a fuel gas and an oxygenous gas that are combusted to give a combustion gas. The combustion gas has a defined composition having a defined partial water vapor pressure. Hydrogen is used in the fuel gas with a proportion of at least 10% by volume. The heat treatment furnace is additionally flooded with a water vapor-free and/or hydrogen-free gas, as a result of which the water vapor-free and/or hydrogen-free gas mixes with the combustion gas so as to bring about a partial water vapor pressure of the mixture in the furnace atmosphere of the heat treatment furnace that is less than the defined partial water vapor pressure of the combustion gas.